Damage Control of Point Pillar Presplitting Blasting in Dahongshan Copper Mine
During underground mining using room-and-pillar method or room-and-pillar subsequent filling mining method,in order to ensure the stability of the quarry,most of the pillars are often reserved to support the upper rock body.Some mining methods used nowadays cause damage to the stability of the pillars to a certain extent,so it is crucial to study and prevent the damage to the pillars.In this paper,the stability of the pillars is investigated by comparing the damage caused by the conventional point-pillar method and the point-pillar boundary pre-cracking and blasting method in the west section of the Dahongshan Copper Mine in the middle of the 180th section of the 360-B144 quarry.The findings show that the damage depth of the conventional point-pillar mining is about 1.47 m,while the damage depth of the point-pillar boundary pre-cracking blasting is about 1.21 m,and the damage impact of the point-pillar boundary pre-cracking blasting on the neighboring pillars is smaller than that of the conventional point-pillar mining.The change of sound velocity of the rock body in the point pillar boundary pre-cracking blasting area is 9.02％,which is smaller than the change of sound velocity of the rock body in the conventional point-pillar blasting area by 14.65％.
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